compositor-drm: Handle unconnected connectors better

If a connector is not attached to a crtc, weston fails to bring it up.
Typically kms fbdev drives all crtc and connectors, but if kms hasn't been
initialzed and weston is the first to set a mode of if a monitor is
hotplugged, we just fail to bring it up.

(krh: reformatted and edited a bit from original patch)
1 file changed